Boom stiffening system

ABSTRACT

The present invention is a boom system comprising a plurality of articulated boom sections. Each boom section has a longitudinal axis. A stiffening layer is attached to a surface of at least one of the boom sections, and extends within about ten degrees of parallel to the longitudinal axis of the boom section. The stiffening layer is formed of a fiber-reinforced composite material including a plurality of fibers and matrix material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Nos.60/271,094 filed Feb. 23, 2001 for “Boom Stiffening System” by T.Anderson, L. Schmidt, D. Bissen, B. Spencer, R. Grover and L. Willner;60/271,095 filed Feb. 23, 2001 for “Conveying Pipeline Mounted Inside ABoom” by T. Anderson, L. Schmidt, D. Bissen, B. Spencer and L. Willner;60/278,798 filed Mar. 26, 2001 for “Composite Material Piping System” byD. Bissen, L. Schmidt, B. Spencer and L. Willner; 60/278,132 filed Mar.23, 2001 for “Boom Utilizing Composite Material Construction” by T.Anderson, D. Bissen, L. Schmidt, R. Atherton, B. Spencer, L. Willner andR. Grover, all of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to a conveying or hoisting boom system. Inparticular, the present invention increases the stiffness and the loadbearing capacity of a conveying or hoisting boom system and attachedpipeline by incorporating a composite reinforcement fiber matrix intoits construction.

Boom systems offer a safe, cost effective and efficient method oflifting a load and reaching to a distant elevated position. Boom systemscan be mounted on portable platforms such as trucks. Truck mounted boomsare used as portable lifting and moving mechanisms, as well as tosupport piping for pumping liquids or semi-liquids (such as concrete,slurries, grout and industrial or waste material). Booms which supportpiping may be used in a variety of applications ranging from pumpingconcrete at construction sites to directing water onto upper stories ofbuildings. Boom systems typically have more than one boom section. Eachboom section has a corresponding actuator assembly which supports andmoves the boom section (for example by articulating or telescoping thesections).

Each boom section acts as a cantilevered beam (with no support laterallyalong its length). Booms are frequently subjected to work conditionswhere the loads supported by the boom system place significant stressand strain upon the boom sections. It is important that the boomsections have a sufficient load bearing capacity to perform suchactivities. Additionally, the boom systems can be subject to excessivevibrations and deflections which can interfere with safe and effectiveoperation. Vibrations, deflections and flexural stresses are used asdesign criteria and serve to limit the operational reach of the boomsystems.

In some applications, the booms must be articulated with a high level ofprecision to allow proper positioning of the boom and to avoid undesiredcontact (or impact) with external objects which can cause damage to theboom sections. Pipelines attached externally to the boom sections areparticularly vulnerable to damage from contact with external objects.The required precise positioning of the boom is hindered by a conditionknown as “boom bounce.” Boom bounce is a periodic movement of the boomproportional to the flexibility and length of the boom and to themagnitude of the applied force. A force which is applied to the boom(particularly if applied at the unsupported distal end) causes flexingof the boom. When the force is released, the boom acts like a spring,oscillating around its equilibrium position. When the boom is subject tosudden acceleration or deceleration, the weight of the boom itself cancause an inertial force to be applied to the boom resulting in the abovedescribed “boom bounce.” It is important, therefore, for each boomsection to be stiff enough to minimize boom bounce.

As mentioned, significant stress and strain can be placed upon the boomsections by the weight of the load being supported by the boom system.Additionally, the weight of the boom itself and any attached pipelinecan cause stress and strain upon the boom sections. Therefore, while itis important that the boom have significant stiffness and load bearingcapacity, it is equally important that the boom and attached pipelinehave as little weight as is reasonably possible. The weight of a boomand pipeline at a boom section distal from the truck must be supportedby the boom sections proximate the truck. Since each boom acts as acantilever, the greater the weight of the boom sections, pipeline, andthe load supported by the boom, the greater the moment generated by theboom with respect to the support system. A “moment” can be defined asthe product of a force and the distance to a particular axis or point.If the boom is extended horizontally, the weight of the boom is movedfarther away from the center of gravity of the boom and support systemcreating a larger moment about the support system. The increased momentcauses an increased likelihood that the boom and support system maybecome unstable from dynamic or static load and tip over. Therefore, anyincrease in weight, will decrease the stability and reach of a boomsystem. If a pipeline is attached to the boom system, it may becantilevered from the end of a boom and must have the ability to supportitself over a span, requiring the pipeline to be strong as well aslightweight.

Stress and strain causing forces can be applied to the boom in a numberof ways. For example, when the boom contacts an external object, or anobject is suspended from the end of the boom, an external force isapplied to the boom. Alternatively, when the boom is subject to suddenacceleration or deceleration, the weight of the boom itself causes aninertial force to be applied to the boom (resulting in the boom bouncedescribed above).

Any pipeline attached to the boom sections is typically used to pumpliquids or semi-liquids under pressure (e.g. using piston style pumps).Typically, forces also act on the pipeline with each stroke of thepiston. The resulting stress on the pipeline and boom sections is called“line shock.” The force from the line shock causes the fluid to pushtransversely and/or longitudinally in a cyclical fashion against thepipe (and therefore the boom), producing a force normal or axial to thelongitudinal axis of the boom. In some styles of pumps, impulse loadscan be imposed on the boom system due to initial pressures (i.e.,pressures which occur when the pump is started) imposed in the system,such as with centrifugal pumps.

Currently, boom sections and piping are typically manufactured of metal(steel, aluminum, etc.). The problem with using metals is that they arelimited in length and reach due to their heavy weight and elasticity.Typical metals used in past boom systems have had a modulus ofelasticity which causes them to easily flex, at least partiallyresulting in the “boom bounce” discussed above. Previously, to addstiffness to the boom system, larger cross-sectional boom sections wereused, adding weight to the boom system. It is problematic, therefore, toproduce a boom system which has strength and stiffness as its materialproperties, while still being lightweight and affordable. Therefore,there is a need in the art for a system which allows for increasing theload capabilities of a conveying or hoisting boom and attached pipelinesystem to withstand forces applied to the systems without significantlyincreasing the weight of the system components.

BRIEF SUMMARY OF THE INVENTION

The present invention is a boom system comprising a plurality ofarticulated boom sections. Each boom section has a longitudinal axis. Astiffening layer is attached to a surface of at least one of the boomsections, and extends within about ten degrees of parallel to thelongitudinal axis of the boom section. The stiffening layer is formed ofa fiber-reinforced composite material including a plurality of fibersand matrix material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a boom system of thepresent invention mounted on a truck.

FIG. 2 is a side view of a second embodiment of a boom system of thepresent invention.

FIG. 3 is a top view of a boom section of the present invention.

FIG. 4 is a side view of a boom section of the present invention.

FIG. 4A is an enlarged view of the portion of area 4A in FIG. 4.

FIG. 5 is a cross-sectional view of a boom section of the presentinvention.

FIG. 5A in an enlarged view of the portion of area 5A in FIG. 5.

FIG. 6 is a side view of a boom section of the present invention.

FIG. 7 is a cross-sectional view of an alternate embodiment of theinventive boom section shown in FIG. 5.

FIG. 8 is a cross-sectional view of an alternate embodiment of theinventive boom section shown in FIG. 5.

FIG. 9 is an cross-sectional view of an alternate embodiment of theinventive boom section shown in FIG. 5.

FIG. 10 is a schematic view of an alternate embodiment of a boom sectionof the present invention.

FIGS. 11 is a side view of an alternate embodiment of a composite boomsystem of the present invention.

FIGS. 12A-12F are alternate embodiments of boom cross-sectional shapesof the present invention.

FIG. 13 is a cut-away perspective view of a composite boom section ofthe present invention.

FIG. 14 is a cross-sectional view of an embodiment of an inventivecomposite pipe section of the present invention.

FIG. 15 is a cross-sectional view of an alternative embodiment of aninventive composite pipe section of the present invention.

FIG. 16 is a cross-sectional view of an alternative embodiment of aninventive composite pipe section of the present invention.

FIG. 17 is a perspective view of a composite pipe of the presentinvention having a window.

FIG. 18 is a perspective view of a composite pipe of the presentinvention with a failure induced bulge.

FIG. 19 is a perspective view of adjoining pipe sections of the presentinvention with mating flange connections.

DETAILED DESCRIPTION

FIG. 1 illustrates a perspective view of a material transport system 10of the present invention. The material transport system comprises a boomsystem 12 and a piping system 14 which may be mounted onto a truck 16,or other suitable support structure. The boom system 12 includes a boomsupport (or turret) 18, a base 20, a base boom section 22A, a middleboom section 22B, an end boom section 22C, a first actuator assembly24A, a second actuator assembly 24B, and a third actuator assembly 24C.The boom sections 22 may be conventional steel construction or may beconstructed using fiber-reinforced thermoset composite materials(discussed later). The piping system 14 includes a series of pipes 26used for transporting flowable materials therein. The piping system 14may be attachable to the boom system 12 as illustrated in FIG. 1, ordisposed within the boom system 12 as will be described later withrespect to FIG. 2.

It should be noted that in the description of the invention embodiments,specific examples of elements such as “base boom section 22A” arereferred to with a reference number that includes an appended letter, inthis case the letter “A.” On the other hand, when elements are referredto generally, no letter is appended (e.g., “boom sections 22”) whichrefers to all of the like elements (e.g., boom sections 22A, 22B and22C) in an inventive embodiment. It should also be noted that in thedescription of the present invention, like reference numerals designatethe same or corresponding parts throughout the several figures of thedrawings, and terms such as “vertical”, “horizontal”, “top” and“bottom”, and the like are used as words of convenience not to beconstrued as limiting terms.

The turret 18 of the boom system 12 is mounted on the base 20. The base20 is mounted onto the truck 16 to support the boom sections 22.Mounting the boom system 12 onto the truck 16 provides a mobile platformfor the boom system 12. It should also be noted that it is within thescope of the present invention to mount the boom system 12 to a varietyof mobile platforms which are not illustrated, including a ship, or atrain or alternatively a variety of immobile support systems. The turret18 is rotatably connected to the base 20. A proximal end 28A of the baseboom section 22A is pivotally connected to the turret 18. A distal end28B of the base boom section 22A is pivotally connected to a proximalend 28C of the middle boom section 22B. Likewise, a distal end 28D ofthe middle boom section 22B is pivotally connected to a proximal end 28Eof the end boom section 22C. A distal end 28F of the end boom section22C is unfixed. Although the boom system 10 has three boom sectionsillustrated in FIG. 1, alternative inventive embodiments of the boomsystem 10 can include any number of boom sections 22.

The first actuator assembly 24A is connected to the turret 18 and to thebase boom section 22A for moving the base boom section 22A relative tothe turret 18. The second actuator assembly 24B is connected to the baseboom section 22A and the middle boom section 22B for moving the middleboom section 22B relative to the base boom section 22A. The thirdactuator assembly 24C is connected to the middle boom section 22B andthe end boom section 22C for moving the end boom section 22C relative tothe middle boom section 22B.

In preferred embodiments, the boom system 12 is hydraulically actuatedand the actuator assemblies 24 are hydraulic piston/cylinder assemblies.It should be noted, however, that the actuator assemblies 24 can be anyother type of actuator assembly capable of producing mechanical energyto rotate the boom sections 22 relative to each other and to the turret18. For example, the actuators 24 can be pneumatic, electrical, or othertypes of actuators known to a person skilled in the art. The actuatorassemblies 24 must also have the capability to hold the boom sections 22stationary with respect to each other and the turret 18. The actuators24 are controlled by an operator to direct the distal end 28F of the endboom section 22C into the desired position. Typically, the turret 18 canbe rotated about a vertical axis with respect to the base 20, utilizinga turret actuator 20A. Rotating the turret 18 allows the entire boomsystem 12 to be rotatable with respect to the base 20.

The embodiment of the present invention illustrated in FIGS. 1 and 2includes the piping system (or pipeline) 14 secured to the boom system12. The piping system 14 is used to direct material (e.g., concrete)which is forced through a series of pipes 26. Typically a piston pump 30(although other types of pumps may be used) forces the material into anintake end 14A of the pipeline 14. The material exits the pipes 26through a delivery end 14B, typically via a delivery hose 32. Thus, theoperator can position the distal end 28F of the end boom section 22C soas to direct concrete pumped through the attached piping system 14 intothe desired location (e.g., a remote concrete form). Typical capacity ofthe pump 30 can vary across different types of pumps. In one embodiment,the capacity can vary from as low as approximately 75 cubic yards ofconcrete per hour to as high as approximately 209 cubic yards ofconcrete per hour, with each cubic yard of concrete weighingapproximately two tons.

As discussed, stresses are generated by the pumping action on the boomsystem 12. The principal stresses from the force of the pumping on thepiping system 14 are longitudinal stresses (parallel to the longitudinalaxis of the pipe 26) and hoop stresses (perpendicular to thelongitudinal axis of the pipe 26). The use of a piston type pump (a pumpis indicated generally at 30 in FIG. 1) to pump concrete can createsubstantial longitudinal stresses as well as hoop stresses in thepipeline 14. As a result, the pipeline 14 must have sufficient strengthto be able to withstand line shocks which occur multiple times perminute (e.g. up to approximately 32 times per minute). In oneapplication, the maximum working pressure of the concrete through thepipeline 14 can vary from approximately 759 lbs per square inch (p.s.i.)to approximately 1233 p.s.i., with the maximum hydraulic pressure of thepump at approximately 5075 p.s.i. The pipeline 14 must be able towithstand the forces exerted by the concrete under pressure from one endof the pipeline 14 to the other, otherwise pipe failure (i.e., ruptureof the pipe) will occur. A general rule of thumb is that the burstpressure of the pipe 26 must be at approximately three times the workingpressure. In one embodiment of the present invention, the piping system14 uses pipes 26 having an inner diameter of approximately five inches.

While the piping system 14 may be mounted to a support structure such asthe truck 16, it should be understood that a portion of the pipingsystem 14 may also extend over open ground(i.e. the pipe can becantilevered from the outermost boom section.) As illustrated in FIG. 2,portions of the piping system (as indicated by reference numbers 26A and26B) can be conventionally mounted to the exterior of the boom sections22, while other portion(s) (as indicated by reference number 26C) can bemounted inside one or more of the boom sections 22.

To provide strength while limiting the weight of the boom system 12and/or the piping system 14, composite materials are used in theirconstruction. Advanced composites or modem structural composites areterms used to describe fiber-reinforced composite materials that havehigh-performance characteristics, generally strength and stiffness.Description and identification of various composite materials can befound in literature such as by Mel M. Schwartz, Composite Materials,Volumes I and II, Prentice-Hall, Inc., NJ 1997, ISBN 0-13-300047-8 andISBN 0-300039-7.

Composite materials are the result of embedding high strength, highstiffness fibers of one material in a surrounding matrix of anothermaterial. The fibers of interest for composites are typically in theform of single fibers. The fibers may alternatively be used as multiplefibers twisted together in the form of a yarn or tow. When properlyproduced, the fibers have very high values of strength and stiffness.Each fiber is typically orthotropic, having different properties in twodifferent directions wherein the greater strength, stiffness andtoughness of a fiber generally lies along its length. The strength andstiffness of the fibers are much greater than that of the matrixmaterial. The fibers are embedded in or bonded to the matrix materialwith distinct boundaries between the fibers. In this form, both thefibers and the matrix material retain their physical and chemicalidentities, yet they produce a combination of properties that cannot beachieved with either of the constituents acting alone. In general, thefibers are strong and stiff compared to the matrix material, and are theprincipal load-carrying members. Some example types of reinforcingfibers include, but are not limited to, the following: glass, carbon(graphite), aramid, polyethylene (PE) and boron.

The matrix material holds the fibers in place in the desiredorientation. The role of the matrix material in a fiber-reinforcedcomposite material is to transfer forces (e.g., stress, or load) betweenthe fibers and protect the fibers from mechanical abrasion andenvironmental degradation. The ability to resist corrosion, distributeforces, provide impact resistance, and provide vibrational dampening allinfluence the choice of the matrix material.

Polymeric matrices are an example of a common type of matrix materialwhich may be used in either the boom system 12 or the piping system 14of the present invention. A polymeric material is made of a large numberof long-chain molecules of similar chemical structure frozen in space.Thermoset polymers are an example of a polymeric matrix and aretraditionally used as a matrix material for fiber-reinforced compositematerials. Common types of thermoset polymers include, but are notlimited to, the following: epoxy, phenolic, polyesters, vinyl esters,polyimides and cyanate esters.

In thermoset polymers, the long-chain molecules are chemically joinedtogether (cross-linked) forming a rigid, three-dimensional networkstructure. This process is called “curing” and is often initiated by acatalyst or accelerator in the resin system which allows the curing totake place at room temperature. An alternative curing method uses theapplication of external heat to initiate the cross-linking process.

A common form in which fiber-reinforced composites are used instructural applications is called a laminate. Laminates are obtained bystacking a number of thin layers of fibers in a matrix to achieve thedesired thickness. Fiber orientation in each layer, as well as thestacking sequence of various layers, can be controlled to generate thedesired physical and mechanical properties for the laminate. When thefiber layer and the matrix layer are joined to form a laminate, eachlayer retains its individual identity and influences the laminate'sfinal properties. The resulting laminate composite consists of layers offibers and matrix material stacked in such a way as to achieve thedesired properties in the desired direction. The ordering of the fiberlayer and the matrix layer may be changed without drastically alteringthe properties of the composite material laminate as a whole. Thenumber, composition and orientation of fibers in the layers vary amongstcomposite laminate materials. Thus, through the use of compositematerials, the boom system 12 and/or the piping system 14 can be formedto strengthen each system 12 and 14 at positions that experience higherstress and strain, which would minimize the amount of strengtheningmaterial needed.

While previously the boom sections 22 could only be strengthened byincreasing the thickness of the metal of which they were formed, theboom system 12 of the present invention incorporates a much smalleramount of composite material, which can be used to achieve the samestrengthening effect. Additionally, the composite material is lighterthan the same amount of metal (e.g., steel). Therefore, constructing theboom sections 22 either partially or entirely from composites provides astronger and lighter boom system 12. The composite fiber matrix on themetal boom section 22 stiffens the boom system 12 while adding aproportionately small amount of weight to the boom system 12.

Numerous advantages can be realized by decreasing the weight of eachboom section 22. One advantage is that the hydraulic power requirementsto operate the actuators can be reduced. Additionally, as each boomsection 22 is reduced in weight, the weight of the entire boom system 12is reduced. Reduction of the dead weight of the boom allows reduction ofthe weight of other boom components, including but not limited to,hydraulic cylinders, guide levers, pins, etc. Weight reductions of theentire boom system will allow lighter weight support systems that aremounted on the truck chassis, (e.g. the turret 18, base 20, and anyrequired outriggers). Any truck system weight which previously wasutilized strictly as ballast can also be reduced or eliminated. Thereduction of the boom system 12 weight allows more flexibility in use ofthe truck 16. An important factor on truck-mounted boom systems is thelevel of axle loading permitted on various roads. Reducing the weight ofthe truck can permit the operator to retract (or eliminate) the “pusher”or “tag” axles which were previously used to comply with therestrictions for traveling on certain roads. Additionally, the size ofthe truck itself may be reduced. Reducing the size of the truck 16results in large cost savings when building the material transportsystem 10 of the present invention. A smaller truck 16 also allows formore maneuverability, allowing the truck 16 to position the boom system12 in more inaccessible areas than would be possible for a larger truck.

Alternatively, modifying an existing boom system 12 allows the boomsystem 12 to accommodate a larger load, or extend the reach of the boomsystem 12 while only minimally increasing its weight. Along these samelines, boom systems 12 with longer boom sections 22 can be used toextend the reach of the boom system 12.

The use of composites either in the form of purely composite boomsections 22, as illustrated in FIG. 1 or as stiffening layers 34 onmetal boom sections 22, as illustrated in FIG. 2 allows the manufacturerto customize the strength of the boom system 12. The boom system 12 canbe strengthened to carry more weight, to reach further, to resist impactforces, to resist impulse forces such as those caused by pumping forces,or to withstand forces acting transversely on the boom sections 22.Additionally, existing boom systems 12 can be strengthened byretrofitting stiffening layers 34 onto the boom sections 22 providing aneconomical upgrade to systems already manufactured. All these objectivescan be accomplished while maintaining the material transport system 10at a weight which allows ease of transportation.

FIGS. 3 and 4 illustrate an exemplary embodiment of one boom section 22using composite materials as stiffening layers 34 in concert withpre-existing styles of boom construction while end boom section 22C isspecifically shown, it should be understood that the discussion withrespect to end boom section 22C is meant to be exemplary for any or allboom sections 22 and in the inventive boom system (illustratedpreviously in FIGS. 1 and 2). The boom section 22 includes top andbottom composite stiffening layers 34A and 34B. The longitudinal axis ofthe boom section 22 is designated by reference number 36. The stiffeninglayers 34A and 34B run substantially parallel to the longitudinal axis36 (preferably within ten degrees of parallel). The boom section 22further includes a foot section (or coupling arm) 38, and a boom arm 40.The foot section 38 functions to rotatably couple adjacent boom sections22 to one another, or to couple boom section 22A to the turret 18 (asshown and described previously with respect to FIG. 1). The boom arm 40is made of steel or other metal and is fixed to the foot section 38(also made of steel, aluminum or other metal), typically by welding.While the inventive embodiment is described using metal boom arms 40,the invention can also be used to strengthen boom sections 22 made ofother materials, including composite boom sections (discussed furtherbelow).

As illustrated in FIG. 4A, the top and bottom composite stiffeninglayers 34A and 34B can be applied to the foot section portion 38 of theboom section 16 as well as to the boom arm portion 40.

The metal boom sections 22 are constructed according to a variety ofmethods generally known to those skilled in the art. Typically, the boomsections 22 are constructed by welding four steel plates 42A, 42B, 42C,and 42D together, as is illustrated by the cross-sectional view of boomsection 22 in FIG. 5. In the illustrated embodiment, the four steelplates 42A-42D form a hollow structure having a rectangular crosssection, although other cross-sectional shapes and materials arecontemplated by the invention. Each steel plate 42A-42D has an exteriorface 44A, 44B, 44C, and 44D, respectively. The top and bottom stiffeninglayers 34A and 34B are bonded to exterior faces 44A and 44C of steelplates 42A and 42C. The stiffening layers 34A and 34B are preferablybonded to the top steel plate 42A and bottom steel plate 42C, sincethese are typically the plates which experience the greatest tensile andcompression forces due to vertical loadings. Thus, by stiffening andstrengthening plates 42A and 42C, the stress is reduced on the platesand the deflection resistance of the boom section is improved. Otherconfigurations are possible, however, including placing stiffeninglayers on the exterior faces 44A-44D of all the steel plates 42A-42D.Although the boom section 22 is shown using four plates 42 weldedtogether, other configurations may be used for the boom section 22(e.g., I-beam, triangular, etc.) without departing from the spirit andscope of the invention. The stiffening layers 34A and 34B are preferablyformed of a reinforcing composite which includes a matrix material andhigh tensile modulus fibers. In one embodiment, the reinforcement fiberis a uni-directional high modulus fiber indicated at 46 in FIG. 5A. Thefibers 46 can be purchased for use in a variety of forms, includingprepreg (fibers pre-impregnated with a thin layer of resin) or preform(fibers in woven form). In one embodiment of the invention, the fiber 46is used in prepreg form and is positioned within a matrix material (orresin) 48 so that the length of the fiber 46 runs generally parallel tothe longitudinal axis of the boom section 22, typically forming an angleless than 20° with the longitudinal axis. Using other angles, however,does not depart from the spirit and scope of the invention.

In alternative embodiments of the present invention, laminated compositematerials may be used as stiffening layers 34. In this configuration,different laminate layers are positioned so that the fibers 46 in onelayer run at a first angle to the longitudinal direction 36 of the boomsection 22 and the fibers 46 in a second layer run at a second angle tothe longitudinal direction of the boom section 22. Preferably, thefibers 46 have a tensile strength of greater than about 390 Ksi(thousand lbs per square inch) and a tensile modulus of greater thanabout 92 Msi (million lbs per square inch).

The fibers 46 have high compressive and tensile material properties(when used in composite materials) in the longitudinal (or lengthwise)direction. The direction in which the fibers 46 are run in thestiffening layers 34 can affect the type of force which can bewithstood. For example, running the fibers 46 transversely allows theboom section 22 to better withstand shear forces. Thus, depending uponthe desired application of the boom section 22, various fiber 46directions can be used to provide customized strength, as will befurther discussed with respect to FIG. 10.

In one embodiment of the present invention, the resin (matrix) 48 is athermosetting resin, such as a polyester or epoxy resin, which iscatalyzed and accelerated by adding chemicals or by applying heat.Alternatively, the resin used may be a vinyl ester. Using vinyl ester asthe resin allows application and curing of the resin at ambientconditions.

As illustrated in FIG. 6, when a downward force P is applied to the boomsection 22, a moment M (as is known to those skilled in the art) isgenerated along the length of the boom section 22, proportional to thedistance from the force P (i.e., moment=force×distance). The result isthat compressive forces 50 act along the bottom plate 42C of the boomsection 22 and tensile forces 52 act along the top plate 42A of the boomsection 22. By running the composite fibers 46 in the longitudinaldirection of the boom section 16 they are disposed so that the tensileand compressive mechanical properties are oriented in the direction ofthe compressive forces 50 and the tensile forces 52, acting to counterthe flexing of the boom section 22. It should be noted that thedescribed placement of the force P and resulting moment M isillustrative and other forces may occur which act along the plates 42 ofthe boom section 22.

To illustrate the effect of the stiffening layers 34A and 34B on theboom section 22, a simplified model of the deflection of a cantileveredbeam with a force applied at one end can be created by using theequation: $Y = \frac{{PL}^{3}}{3{EI}}$

where:

Y is the distance the beam is deflected;

P is the load applied;

L is the length of the beam;

E is the modulus of elasticity (or the tensile modulus or Young'sModulus); and

I is the moment of inertia of the cross section of the beam.

The product E multiplied by I (or EI value) is known as the flexuralrigidity (or stiffness). Increasing the EI value has the effect ofdecreasing the amount of deflection of the beam for a specific load(s).One method of increasing the EI value of a beam is to increase the “I”value of the beam. To do this, the cross-sectional dimensions (size) ofthe beam must be increased. Increasing the cross-section of the beam(formed from the same material, e.g., steel) results in an increase inthe weight of the beam. The second method of increasing the EI value isby forming the beam from a material having a larger modulus ofelasticity (E). Evaluating the effect of the stiffening layer 34 can beaccomplished by comparing the EI value of a first steel beam with nostiffening layer to the stiffness of a second smaller (and lighter)steel beam utilizing the composite stiffening layer.

Consequently, the stiffness (or EI) value of the first beam can beobtained due to a large moment of inertia (I) value. The same stiffnessvalue can be obtained in the second beam, however, using a smallermoment of inertia by manufacturing the second beam using a materialwhich has a larger modulus of elasticity than the material of the firstbeam.

The following example illustrates the effect of adding a composite layerto the boom system 12. The steel plates 42A-42D in the boom sectiontypically have a modulus of elasticity of approximately 29 msi. Thematerial property numbers chosen for the stiffening layers 34 areexemplary only, (e.g., thickness, elasticity). Other property values maybe chosen according to the desired application. For this example, thestiffening layers 34A and 34B have a modulus of elasticity ofapproximately 54 msi. The stiffening layers 34A and 34B have a thicknessof approximately 0.100 inches on the top plate 42A and the bottom plate42C. Thus, using the stiffening layers 34A and 34B greatly reduces thesize of the boom section 22 (as indicated by the size of its moment ofinertia (I)) while still maintaining the same stiffness (EI). This isshown by the following equation:

EI _(Unstiffened Steel Beam (USB)) =EI _(Stiffened Beam (SB)) +EI_(Composite Stiffening Layer (CSL))

E_(USB)=E_(SB)=29 msi

E_(CSL)=54 msi

I_(USB)=71.96 in⁴

I_(CSL) for a composite layer 0.100 inch thick=14.91 in⁴

Solve for I_(SB)

(71.96 in⁴)(29 msi)=(I _(SB))(29 msi)+(14.91 in⁴)(54 msi)

I_(SB=)44.20 in⁴

Thus, the use of the stiffening layer 34 (having a thickness of 0.100inches) decreases the moment of inertia required of the steel beam from71.96 in⁴ to 44.20 in⁴ while still maintaining the same level ofstiffness. The formula for the moment of inertia of the beam, about anaxis parallel to the centroidal axis of the beam is:

I=Σ{fraction (1/12)} bh³ +Ad ²

where: b=the base dimension of each plate 42A-42D in the cross section

h=the height dimension of each plate 42A-42D in the cross section of thebeam

A=the area of the cross section of each plate 42A-42D

d=the distance between the beam centroidal axis and the parallel axisabout which rotation occurs.

It can be seen from the above equation that the dimensions of the steelbeam can be reduced if the I value is reduced. It follows that using thecomposite material in addition to an existing steel beam strengthens thebeam, whereas redesigning the beam to incorporate composites whilemaintaining the same levels of strength and flexibility allows adecrease in the amount of steel used in the beam. Since the compositesare stronger and lighter than steel (roughly three times lighter and twotimes stronger) the entire beam can be much lighter, while maintainingits strength.

Affixing the stiffening layers 34 to the boom sections 22 creates theability to manufacture larger and longer boom sections 22 by maintaininga required level of stiffness without drastically increasing the weightof the boom system 12. Additionally, by adding stiffening layers 34 toan existing boom system 12 (i.e., retrofitting the system) the capacityof an already existing boom system 12 can be increased.

FIG. 7 illustrates an embodiment of the present invention wherein thetop and bottom stiffening layers 34A and 34B are applied “wet” to theboom section 22. When using the “wet” application method, the top andbottom stiffening layers 34A and 34B are formed directly on the exteriorfaces 44A and 44C of the top and bottom steel plates 42A and 42C. Fibersare positioned in place on the boom section 22 and resin is applied.When the resin is cured (in a manner known in the art), it bonds to theexterior faces 44A and 44C of the top and bottom plates 42A and 42C,fixing the stiffening layers 34A and 34B in place. Additional layers 34can be positioned and cured such that the fibers are disposed anyorientation in order to achieve desired strengthening characteristics.

FIG. 8 illustrates an alternative embodiment of the present inventionwherein prefabricated (pultruded, extruded, cast, etc.) top and bottomstiffening layers 34A and 34B are affixed to the exterior faces 44A and44C of the top and bottom steel plates 42A and 42C of the boom section22 using an adhesive 54. This manner of fixation allows an existing boomsystem 12 to be upgraded using the extruded composite stiffening layers34A and 34B, which are formed separately from the boom section 22. Theycan then be applied to the boom system 12 (either at a manufacturingfacility or transported to a work site) and affixed to the boom section12. This method of affixing the stiffening layers 34A and 34B provides aconvenient method to upgrade the strength of a previously manufacturedboom system 12. The adhesive 54 used is preferably epoxy (although otheradhesives may be used). The adhesive 54 is applied to the outer surfaces44A and 44C. The stiffening layers 34A and 34B are then pressed onto theadhesive 54, and the adhesive is allowed to cure. Thus, each of thestiffening layers 34A and 34B is secured to each boom section 22.

The stiffening layers 34A and 34B may alternatively be mounted to theboom system 12 using mechanical fasteners, as illustrated in FIG. 9.Bolts 56 (or other fasteners known in the art such as rivets, screws,etc.) are disposed through apertures 58 in the stiffening layers 34 andtop and bottom steel plates 42A and 42C. Alternatively, fasteners may bescrewed through the stiffening layers 34A and 34B (using, for example,self tapping screws). Once again, this fixation method allows theextruded stiffening layers 34A and 34B to be affixed to the boom section22 and can be used to easily retro-fit pre-existing boom systems 12 withstiffening layers 34. Although only four bolts 56 are shown in FIG. 9,additional fasteners would typically be used to secure the stiffeninglayers 34A and 34B to the boom section 22.

In various embodiments, the thickness of the composite layer 34 may beincreased to increase the stiffness of the boom sections 22.Additionally, stiffening layers 34C, 34D, 34E and 34F can be secured toeach of the steel plates 42A-42D of the boom section 22, as illustratedschematically in FIG. 10. Once again, the placement of the stiffeninglayers 34 and the direction of fibers 46 within each stiffening layer 34determines the direction upon which strength is provided to the boomsection 22. If a layer having generally longitudinal fibers 46A ismounted to the top plate 42A (as shown by the composite stiffening layer34C), the boom section 22 is able to better withstand applied forceswhich bend the boom section 22 about a horizontal axis 60 (such as byloads attached to the boom system 12, or by the weight of the boomsections 22 themselves). If a layer having generally longitudinal fibers46B is mounted to the side plate 42B (as shown by the compositestiffening layer 34D), the boom section 22 is better able to withstandforces which bend the boom section 22 about a vertical axis 62 (such asmay occur when the boom section contacts an external object).Additionally, the direction which the fibers 46 are run in thestiffening layers 34 can affect the type of force which can bewithstood. For example, if a layer having fibers 46C runningtransversely is mounted to side plate 42D, (as shown by compositestiffening layer 34F) allows the boom section 22 to better withstandshear forces. Thus, depending upon the type of application the boomsection 22 is used in, various fiber 46 directions can be used toprovide customized strength.

In addition or in the alternative to stiffening layers 34, compositematerial may be used to construct the boom section 22 itself. Analternate embodiment of a composite boom system 12 is illustrated inFIG. 11. In this embodiment, at least one and alternatively all of theboom sections 22 are constructed substantially of thermoset compositematerials. Similar to the use of stiffening layers 34, the use oflightweight composites to form each boom section 22 has multipleadvantages (e.g., increased truck stability, etc.). Since each of theentire boom sections 22 are formed of composite materials, the weight ofthe entire boom system 12 can be dramatically reduced compared to priorart boom systems. The lightweight composite boom system 12 of thepresent invention has a smaller hydraulic power requirement than a steelcomposite boom system having similar strength. By reducing the weight ofthe boom system 12, components used in conjunction with the boom system12, such as hydraulic cylinders, guide levers, pins, etc, can be reducedin weight as well, because the stresses imposed by the boom system 12are reduced. Additionally, truck weight and axle weight can also bereduced, thereby reducing road restrictions applicable to the vehicleused to support the boom system 12.

Lightweight composite boom sections 22 may be used to extend thevertical and/or horizontal reach of conveying boom systems 12 past thatof prior art metal boom systems utilizing similarly sized steel boomsections 22. The boom system 12 is cantilevered, so that eachintervening boom section 22 (e.g., middle boom section 22B) supports theweight of the more distal boom sections (e.g., middle boom section 22Bsupports the end boom section 22C, and base boom section 22A supportsthe combined loads of middle and end boom sections 22B and 22C).Constructing the boom sections 22 substantially of lightweightcomposites, reduces the weight added to the total load of the boomsystem 12 by each of the boom sections 22 and allows the boom system 12to be built with a greater vertical and/or horizontal reach.

As was described with respect to utilizing stiffening layers 34,composites can be used in one, some, or all of the boom sections 22. Notusing composites in all the boom sections 22 provides combinations ofsteel boom sections and composite boom sections which can reduce theoverall costs when compared to constructing an entire boom system 12 ofcomposite materials, while still attaining benefits from the use of thecomposite materials. An advantageous boom system embodiment thatbalances utility with costs constructs the outermost boom section (inthe illustrated embodiment, end boom section 22C) using fiber-reinforcedthermoset composite materials, while constructing the remaining boomsections 22 of steel. This “hybrid” embodiment of the boom systemprovides stability to the boom system 12 by decreasing the weight of thedistal end 64 of the boom system 12. The overall reduction in weight ofthe boom system 12 decreases the overturning moment when the boom system12 is extended, thereby increasing stability. Thus, utilizing acombination of steel boom sections with composite boom sectionsgenerates a large increase in performance by the boom system 12 withminimal increase in expense which may be incurred by utilizing compositematerials.

Any combination of metal boom sections 22 in combination with compositeboom sections 22 is contemplated by the invention. For example, thesecond and third boom sections 22B and 22C may be made of compositematerials, while the first boom section 22A is metal. Additionally, anynumber of boom sections may be utilized in the boom system 12 of thepresent invention. Also, any combination of composite boom sections tocomposite stiffened metal boom sections may be used without departingfrom the spirit and scope of the invention.

As discussed above, an advantage of composite materials is the abilityto choose materials and forming techniques so as to achieve the desiredqualities for the boom sections 22. Fiber-reinforced composite materialsconsist of fibers with high strength and modulus embedded in a matrix.When the fiber and matrix are joined together, they both retain theirindividual characteristics and both influence the composite material'sfinal properties directly.

When designing entire boom sections 22 of composite materials,properties of interest include, but are not limited to the following:tensile strength, stiffness, vibrational dampening, impact resistance,corrosion resistance and weight reduction (versus steel booms). Inherentvibrational dampening is one benefit of fiber-reinforced compositematerials over conventional steel-type boom sections.

Boom sections 22 may be constructed of composite materials according toa variety of methods generally known to those skilled in the art. In oneembodiment each boom section 22 has a long rectangular shape with aslight taper resulting in a smaller circumference at the distal end 28Bof each boom section 22 than at the proximal end 28A. FIGS. 12A-12Fillustrate alternative embodiments of boom sections 22 having varyingcross-sectional shapes. Possible cross-sectional shapes for individualcomposite boom sections 22 include, but are not limited to, rectangular66 as illustrated in FIG. 12A, ovular 68 as illustrated in FIG. 12B,circular 70 as illustrated in FIG. 12C, elliptical 72 as illustrated inFIG. 12D, hexagonal 74 as illustrated in FIG. 12E and radiusedrectangular 76 as illustrated in FIG. 12F. These shapes are exemplary ofcross-sectional shapes which could be used for each boom section 22, andmany additional shapes may be utilized without departing from the spiritand scope of the invention.

As illustrated in FIG. 13, the shape of each boom section 22 iscontrolled by the shape of a mandrel 78 that is used in boomconstruction. The mandrel 78 is usually a hollow steel mandrel with aslight taper. Any suitable form may be used, however, including solidforms or forms made of materials such as aluminum or balsa.Additionally, additional pieces of material can be attached to anexisting mandrel 78 to alter the shape of the mandrel. For example, tocreate the radiused rectangular shape 76 of the boom section 22illustrated in FIG. 13, two internal sandwich blackouts 80 are attachedon the narrow sides of the steel mandrel 78. In one embodiment, theouter dimensions of the steel mandrel 78 are approximately 4 inches byapproximately 6.5 inches. Additionally, the blockouts 80 have a radiusof approximately 2.39 inches and are attached to the mandrel 78.Attaching the blockouts 80 to the mandrel 78 creates a form 82. Theoutside of the form 82 is coated with a layer of wax 84 (preferablyapproximately {fraction (1/16)} inch thick) to aid in the removal of theform 82 after forming the composite boom section 22.

In one embodiment, constructing the composite material boom section 22entails applying several layers (or lamina) composed of fibers embeddedin a resinous or polymeric matrix over the form. The end result is boomsection 22 formed from a unified composite material laminate. Typically,individual fibers are too small to work with, so they are bundled intostrands, which are grouped and wound onto a cylindrical forming packagecalled a roving. The rovings are used in continuous molding operationssuch as filament winding. The fibers can be pre-impregnated with a thinlayer of the polymeric resin matrix or applied wet where the fiber iscoated with the resin solution just before application. The volumedistribution between the two components is approximately 60% fiber, andapproximately 40% resin.

One method to apply composite layers is by using the process of filamentwinding. The fiber (from a roving) is fed from a horizontallytranslating delivery head (not shown) to the rotating wax-coated form82. The angle of the fiber with respect to the longitudinal axis of theform is called the wind angle. The angle is typically varied fromapproximately 20° to approximately 90°. The properties of the boomsection 22 depend strongly on the wind angle of the fibers. A feedcarriage (not shown) moves backward and forward causing the fibers tocrisscross at plus and minus the wind angle, creating a weaving orinterlocking pattern. After winding, the composite is cured by methodsdictated by the resin composition chosen.

One embodiment in particular is illustrated in FIG. 13. A first layer ofcomposite material 86 is applied over the wax-coated form by utilizingglass fibers 86A embedded in a vinyl ester matrix 86B. S-2 glass fibersare chosen for their high tensile strength of approximately 4.30 (GigaPascals) GPa. S-2 glass fiber is one of several kinds of glass fiber,and is a lower cost version of S-glass. Other glass fibers such asS-glass or other fibers such as aramid that have similar tensilestrength could be substituted for the S-2 glass and achieve the desiredfinal properties. The glass fibers 86A are applied wet, coated with VE8084, a vinyl ester resin, utilizing the filament winding processdescribed above. A preferable embodiment has a wind angle of 20°,although the angle could be varied within a narrow range and achievesimilar final properties. The first layer 86 is then cured bymaintaining the first layer 86 at room temperature for approximately twohours (or in a manner known to those skilled in the art). Preferably,the resulting S-2 glass/VE8084 layer 86 is approximately 0.14 inchesthick after curing.

A second composite material layer 88 is comprised of carbon fibers 88Aembedded in an epoxy resin 88B. Typically, the second composite layer 88is applied over the first composite layer 86 using a film adhesive layerto hold the carbon fibers in place until the epoxy is applied and cured,but alternative applications of the layers are within the scope of thepresent invention. The carbon fibers in the second composite layer 88are used to provide stiffness to the boom section 22 because of theirvery high tensile modulus. Fibers with a tensile modulus ofapproximately 91 Msi are used in a preferred embodiment.

The carbon fibers 88A of the second composite layer 88 are wound ontothe form using a process called polar winding. The fibers 88A are woundabout the longitudinal axis of the form 82. The fiber bands preferablylie adjacent to each other and there are no crossovers. In oneembodiment, the carbon fibers 88A are hand-laid at approximately a 0°wind angle on the radiused ends only. The epoxy resin is then brushed orsprayed onto the fibers. Preferably, the resulting second compositelayer 88 is approximately 0.05 inches thick after curing. Additionalcarbon fiber layers may be used to increase the stiffness and strengthof the boom as is desired.

A flex core layer 90 of aluminum is applied over the second compositelayer 88. The flex core layer 90 acts as a shock absorber or toughnessenhancer to protect the first composite material layer 86 and the secondcomposite material layer 88 from any impact on the boom which coulddamage the integrity of these layers. Typically, the flex core layer 90has an accordian or a honeycomb configuration through its thicknesswhich allows the flex core layer 90 to absorb the impact by compressing(or being “crushed”). In one embodiment, the flex core layer 90 has acrush strength of approximately 500 psi. In other words, the flex corelayer 90 can dissipate the energy of an impact up to 500 psi. The flexcore 90 preferably has a density of approximately 5.1 lb/ft³ inches anda thickness of approximately 0.5 inches.

A third composite material layer 92 is applied over the aluminum flexcore 90 to provide impact resistance. The third layer 92 comprisesaramid fibers 92A embedded in a vinyl ester (VE 8084) resin matrix 92B.Aramid fibers have high tensile strength to weight ratios and areresistant to impact damage. In the preferred embodiment the aramid fiber92A is helically wound in a manner similar to the first layer 86. Apreferred embodiment has a wind angle of approximately 30°, although theangle could be varied. The resulting third composite layer 86 has apreferable thickness of approximately 0.083 inches after curing forapproximately two hours at room temperature.

A fourth composite material layer 94 is an additional S-2 glass/VE 8084layer including glass fibers 94A coated in epoxy resin 94B. The purposeof the fourth composite layer 94 is to add additional strength andimpact resistance. The fourth layer 94 is helically wound in a mannersimilar to the first composite layer 86, but at a wind angle ofapproximately 60° (other wind angles may be used), preferably having athickness of approximately 0.030 inches.

After layers 86, 88, 90, 92 and 94 are disposed about the form 82 andthe layer of wax 84, form 82 is removed, leaving the completed (hollow)composite boom section 22. This may be accomplished by heating thecompleted boom section 22 in order to soften the wax 84, allowing theform to slide longitudinally out from inside the layers 86, 88, 90, 92and 94.

The composite boom section 22 formed in the above-described manner hasapproximately the same stiffness as a comparable steel beam withapproximately half of the weight. The EI value (stiffness) of a steelboom section 22 is approximately 786×10⁶lb.²ft.s²/in² with anapproximate weight of 0.849 lbs/in., whereas the composite boom section22 has a calculated EI value of approximately 759×10⁶ lb.²ft.s²/in² withan approximate weight of 0.447 lbs/in. As discussed previously, lighterweight boom systems 12 are beneficial because of the reduction in boombounce and ability to more easily transport the boom systems 22.Composite boom systems 12 are especially useful when the boom structures22 are utilized for the conveyance of concrete, slurries, grout andindustrial or waste material. These materials are often dense andabrasive, requiring heavy pipe 26 to withstand the materials themselvesand the pressure from the pumps to flow the material. The boom system 12must be able to support both the heavy pipe 26, the concrete at 150 lbsper cubic foot, and the extended boom sections 22. The composite boomsections 22 of the present invention and the overall boom system 12 aremuch lighter than conventional steel boom systems of the prior art,while still maintaining similar superior strength and stiffnesscharacteristics.

To further reduce the weight of the material transport system 10, atleast some of the piping system 14 may be constructed of compositematerials, as illustrated in FIG. 14. As with the boom sections 22, anadvantage of composite materials used in constructing the pipes 26 isthe ability to select materials that achieve the desired qualities for aparticular application while markedly reducing the weight of thematerial transport system 10. When designing the pipes 26 for use withthe boom system 12, properties of interest include, but are not limitedto, the following: tensile strength to resist hoop and longitudinalstresses, vibrational dampening, impact resistance, abrasion resistanceand thermal expansion.

When forming the composite pipe sections 12, the composite materials areusually arranged in layers (as was discussed with respect to thecomposite boom sections 22 in FIG. 13). These layers adhere togetherduring curing to form a unified laminate. The fibers in each layer areoriented in such a way as to achieve the desired properties in one ormore directions. The ordering of the layers may be changed to alter theproperties of the composite material laminate as a whole. The number,composition and orientation of fibers in the layers may vary amongstcomposite laminate materials according to the desired properties of thefinal cured (or hardened) material.

Each composite pipe 26, as illustrated in FIGS. 14 through 18, may beconstructed according to a variety of methods generally known to thoseskilled in the art. In one embodiment, pipe sections 26 are constructedusing fiber-reinforced, thermoset composite materials. Forming thecomposite pipes 26 of the piping system 14 can be accomplished insubstantially the same manner as was described with respect to the boomsections 22 formed of composite materials. Individual fibers are bundledinto strands, which are grouped and wound onto a roving. The rovings areused in continuous molding operations such as filament winding and arepre-impregnated with a thin layer of polymeric resin matrix (prepreg) orapplied wet where the fiber is coated with the resin solution justbefore application. Again, the preferred volume distribution between thetwo components is approximately 60% fiber and approximately 40% resin.During filament winding, the fiber is fed from a horizontallytranslating delivery head to a rotating wax-coated mandrel. The windangle can be varied from 20° to 90°. Most preferably, the wind angle isat 54° to the longitudinal axis of the mandrel, providing balancedstrength to the piping 26 in both the longitudinal and transversedirections. After winding, the composite material is cured by methodsdictated by the resin composition chosen.

FIG. 14 illustrates one embodiment of the pipe section 26 using a liner98 made of abrasive resistant materials inserted inside a pressure tube100 made of fiber-reinforced thermoset composite materials. An annularspace 102 is disposed between the liner 98 and the pressure tube 100.The liner 98 may be made of aluminum, steel or fiber-reinforcedthermoset composite materials chosen to withstand abrasion. The pressuretube 100 is preferably constructed of layers of fiber-reinforcedthermoset composite materials chosen to provide strength to withstandhoop and longitudinal stresses on the pipe 26. The annular space 102between the liner 98 and the pressure tube 100 allows the liner 98 to beremoved and replaced as it becomes worn by contact with the concrete orother abrasive materials. Alternatively, the liner 98 may be maintainedin the pressure tube 100 using stops 104 glued or bolted into thepressure tube 100. Compressible stops 104(such as rubber stops) arepreferably used to accommodate differential thermal expansion of thepressure tube 100 and liner 98.

FIG. 15 illustrates an alternative embodiment of composite pipe section26. An outer composite pressure tube 106 may be applied directly over ametal liner tube 108. In one embodiment, The composite pressure tube 106preferably has an outer diameter of approximately 5.625 inches and aninner diameter of approximately 5.25 inches. In one embodiment, theliner tube 108 preferably has an outer diameter of approximately 5.25inches and an inner diameter of approximately 4.88 inches.

FIG. 16 illustrates another alternative embodiment of composite pipesection 26 wherein the pipe section 26 is composed of onlyfiber-reinforced thermoset composite materials. The composite materialsare chosen so that an inner surface 110 of the pipe 26 is resistant toabrasive materials (e.g., concrete). An outer surface 112 is formed of afiber-reinforced thermoset material chosen for its impact resistantqualities. Positioned between the inner surface 110 and outer surface112 are additional layers 114 of fiber-reinforced thermoset materialsformed to give the pipe 26 strength to withstand both longitudinal andhoop stresses.

FIG. 17 illustrates an alternative embodiment of pipe section 26utilizing a clear window 116 inserted into the wall of the pipe section26 to allow visual inspection of the material flow therein. The window116 may be constructed within the pipe section 26 so as not to reducethe structural integrity at the window location. The window 116 may beformed of thermoset materials, fiber-reinforced composite materials orany other materials capable of withstanding the pressure and abrasion ofcontact with the contents of the pipe section 26.

An advantage provided by the use of composite materials in constructingthe piping system 14 is illustrated in FIG. 18. One embodiment of thefiber-reinforced thermoset composite pipe section 26 is shown. A bulge118 has formed in the pipe section 26, indicating that the compositematerial is failing. In conventional piping (e.g. metal piping), failureoccurs without warning by direct rupture of the pipe 26. The contents ofthe pipe 26 are able to exit through the rupture. The composite pipesection 26 of the present invention can be constructed so that when thepipe 26 begins to fail, the polymer and fiber network in the compositematerial plastically deform outward, forming the bulge 118. The visiblebulge 118 allows the operator of the material transport system 10 torelease the pressure on the boom section 22 before the pipe section 26fully ruptures. The failed pipe section 26 can then be replaced.Previously, failure in the pipe meant that the pipe ruptured resultingin loss of contents and possible damage to surrounding equipment andworkers. Therefore, the bulge 118 which forms in the current embodimentsaves in downtime and cleaning, providing an economic advantage overprior art pipe systems. This benefit is enhanced by the fact that thelocation of points of highest wear can be predicted in advance along thepiping system, and the composite pipe can be designed accordingly.

As illustrated in FIG. 19, the composite materials used to form thepiping 26 can be machined or manufactured to form various connections120 between lengths of piping such as raised ends for mechanical clampconnections, bolted flanged connections, threaded connections, solventwelded connections and bell and spigot connections (among others knownin the art). These connecting methods may be formed into piping 26 as itis layered and cured (as discussed), may be machined into the piping, ormay be formed separately and adhered to the piping. Additionally, pipingbends and corners can be formed into the piping as the length of pipingis layered and cured such that the bend and/or corner portion isintegral to each pipe length. This is in contrast to metal pipes, whichtypically require a bend or corner portion to be mechanically connected(e.g., by a mechanical clamp, welding, etc) to straight portions ofpiping. It should also be noted that composite piping can be utilizedwith any combination of composite boom sections and metal boom sections,(either stiffened with composite layers or unstiffened) withoutdeparting from the scope of the invention.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A boom system comprising: a plurality ofarticulated boom sections, each boom section having a longitudinal axis;a concrete pipeline having an intake end and a discharge end, thepipeline supportably engaged to at least one of the boom sections; aconcrete pump attached to the intake end of the pipeline; and astiffening layer attached to a surface of at least one of the boomsections, and extending within about ten degrees of parallel to thelongitudinal axis of the boom section, wherein the stiffening layer isformed of a fiber reinforced composite material including a plurality offibers and a matrix material.
 2. The boom system of claim 1 wherein thefibers in the composite material are disposed so as to be generallyparallel to the longitudinal axis of the boom sections.
 3. The boomsystem of claim 2, wherein the fiber orientation of the compositematerial is disposed at an angle of twenty degrees or less to thelongitudinal axis of the boom section.
 4. The boom system of claim 3,wherein the fibers comprise carbon and the matrix material is selectedfrom the group consisting of: vinyl, ester, epoxy polymers andcombinations of any of these.
 5. The boom system of claim 1 and furthercomprising: an adhesive disposed between the stiffening layer and thesurface of the boom section wherein the adhesive acts to secure thestiffening layer to the surface of the boom section.
 6. The boom systemof claim 1 further comprising mechanical fasteners suitable for securingthe stiffening layer to the boom section.
 7. The boom system of claim 1,wherein the composite material is applied wet to the boom section andambiently cured to adhere the stiffening layer to the boom section. 8.The boom system of claim 1 wherein the stiffening layer includesmultiple layers of fibers, wherein at least two layers are disposed sothat the fibers in one layer are disposed at an angle to the secondlayer.
 9. The boom system of claim 1 wherein at least a portion of thepipeline is formed of fiber reinforced composite material.
 10. Amaterial transport system comprising: a truck having a boom support; aplurality of boom sections supported by the truck, wherein each boomsection has a longitudinal axis and wherein the boom sections areinterconnected by a plurality of actuators; a concrete pipelinesupportably engaged with at least one of the boom sections, the pipelinehaving an intake end and a discharge end; a concrete pump connected tothe intake end of the pipeline; and a stiffening layer attached to asurface of at least one of the boom sections, the stiffening layer beingformed of a fiber-reinforced composite material including a plurality offibers and a matrix material.
 11. The system of claim 10 wherein thefibers in the fiber-reinforced composite material are disposed so as tobe generally parallel to the longitudinal axis of the boom section. 12.The conveying boom of claim 10 wherein the composite material is appliedwet to the surface of the boom section and ambiently cured so as tosupply adhesion and load transfer to the at least one boom section. 13.The system of claim 10 further comprising an adhesive disposed betweenthe stiffening layer and the surface of the boom wherein the adhesiveacts to secure the stiffening layer to the boom section.
 14. The systemof claim 10 further comprising mechanical fasteners secured to the boomsection and the stiffening layer, the mechanical fasteners securing thestiffening layer to the boom section.
 15. The system of claim 10 whereinthe plurality of boom sections comprise: a first section rotatablycoupled to the boom support; and an end section supported by the firstsection.
 16. The system of claim 15, wherein the boom sections areconstructed of steel.
 17. A material transport system comprising: atruck; a boom system including a base boom section rotatably coupled tothe truck; a middle boom section pivotally connected to the basesection; an end boom section having a first end pivotally connected tothe middle boom section; a pump attached to the truck, the pump havingan outlet; a piping system having a first end connected to the outlet ofthe pump to receive flowable material emitted from the pump and a secondend allowing the dispensing of the received material; and a plurality ofcomposite stiffening layers, the stiffening layers fixably attached toat least one of the base boom section, the middle boom section and theend boom section.
 18. The material transport system of claim 17 whereinthe composite stiffening layers comprise multiple layers of fibers,wherein at least two layers are disposed so that the fibers in one layerare disposed at an angle to the second layer to increase the strength ofthe stiffening layer isotopically.
 19. The material transport system ofclaim 17 wherein the composite stiffening layers comprise; a thermosetpolymeric matrix; and fibers embedded within the matrix.
 20. Thematerial transport system of claim 19 wherein the thermoset polymericmatrix is selected from a group consisting of: epoxy, polyester, andvinyl ester.
 21. The material transport system of claim 19 wherein thefibers are selected from a group consisting of: carbon, aramid,polyethylene, boron, and glass.
 22. A stiffening layer comprising: acured fiber-reinforced composite material including a plurality offibers and matrix material; a longitudinal dimension and a transversedimension such that the stiffening layer is adapted so as to be mountedto boom sections of a truck mounted boom system; and a securing meansadapted to secure the cured composite material to the boom sections ofthe truck mounted boom system.
 23. A method for stiffening boom sectionsof a boom system comprising: forming a fiber-reinforced compositematerial; and attaching the fiber-reinforced composite material to theboom sections.
 24. The method of claim 23 further comprising: disposingfibers in the fiber-reinforced composite material along a longitudinalaxis of the boom sections.
 25. A boom section comprising: a plurality ofplates fixed together, each plate having a surface and a longitudinalaxis, the plates disposed so that the longitudinal axes of the platesare substantially parallel; and a least one stiffening layer attached toat least one surface on the plates and extending within about tendegrees of parallel to the longitudinal axis of the plates, wherein thestiffening layer is formed of a fiber-reinforced composite materialincluding a plurality of fibers and a matrix material.
 26. The boomsection of claim 25 wherein the plates are steel.
 27. The boom sectionof claim 25 wherein the plates are a composite material.
 28. The boomsection of claim 25 wherein the plates are aluminum.
 29. A boom systemcomprising: a plurality of articulated boom sections, each boom sectionhaving a longitudinal axis; and a stiffening layer attached to a surfaceof at least one of the boom sections, and extending within about tendegrees of parallel to the longitudinal axis of the boom section,wherein the stiffening layer is formed of a fiber-reinforced compositematerial including a plurality of fibers and a matrix material.